235/45R18 tire size
A 235/45R18 tire is 26.3 inches tall and 9.3 inches wide. Here are its full dimensions, what the numbers mean, and the sizes you can swap it for.
- Overall diameter
- 26.33″ (669 mm)
- Section width
- 9.25″ (235 mm)
- Sidewall height
- 4.16″ (106 mm)
- Wheel diameter
- 18″
- Circumference
- 82.7″
- Revolutions per mile
- 766
What 235/45R18 means
- 235: the tire is 235 mm (9.3 in) wide from sidewall to sidewall.
- 45: the sidewall is 45% of the width, 105.8 mm (4.16 in) tall.
- R: radial construction, used by almost every modern tire.
- 18: it fits a 18-inch wheel.
Overall diameter = 18 + 2 × 4.16 = 26.33 inches.
Sizes equivalent to 235/45R18
These sizes are within 3% of the overall diameter, the usual limit for swapping without speedometer problems.
| Size | Diameter | Difference | Speedometer at 60 mph |
|---|---|---|---|
| 235/40R19 | 26.4″ | +0.3% | 60.2 mph actual |
| 225/35R20 | 26.2″ | -0.5% | 59.7 mph actual |
| 215/50R18 | 26.5″ | +0.5% | 60.3 mph actual |
| 235/35R20 | 26.5″ | +0.6% | 60.3 mph actual |
| 225/40R19 | 26.1″ | -0.9% | 59.5 mph actual |
| 215/45R19 | 26.6″ | +1.1% | 60.7 mph actual |
| 255/40R18 | 26.0″ | -1.1% | 59.3 mph actual |
| 255/35R19 | 26.0″ | -1.1% | 59.3 mph actual |
| 225/45R18 | 26.0″ | -1.3% | 59.2 mph actual |
| 245/45R18 | 26.7″ | +1.3% | 60.8 mph actual |
Going a size taller? 245/45R18 is 26.7″ tall, 1.3% more than 235/45R18. Compare any two sizes in the tire size calculator.
See every common size side by side in the tire size chart.
Questions
What is 235/45R18 in inches?
A 235/45R18 tire is about 26.3 inches tall (669 mm) and 9.3 inches wide, on a 18-inch wheel. In flotation sizing that's roughly 26.3x9.3R18.
How tall is a 235/45R18 tire?
The overall diameter is 26.33 inches: the 18-inch wheel plus two 4.16-inch sidewalls. Actual tires vary by a few tenths of an inch between brands and models.
Can I put 245/45R18 instead of 235/45R18?
245/45R18 is 0.35 inches taller (1.3%) and 10 mm wider. That's within the usual 3% limit, but check that your wheel width is approved for it and that it clears the suspension.
How many revolutions per mile does a 235/45R18 make?
About 766 revolutions per mile, from a circumference of 82.7 inches.
